Belt Drive Clutch Bearing Install

Cowboy Don · Nov 5, 2013

Might be a stupid question, and I'll probably kick myself when someone posts a solution, but how do I fit a new clutch bearing without damaging it?
First off, my belt kit is so old that I have no idea what brand it is. I'd say it was fitted in the late 80's, at which point I was still a young lad dreaming of owning a badass Commando

So, I drive it into the clutch hub, where the outer race is held in with a circlip:

Then I have to drive the clutch centre through the ID of the bearing from the other side of the hub, and then another circlip is used to hold the inner race

Here's what I'm thinking, after fitting the bearing to the hub, I fit the old bearing in behind it to provide support while driving the centre in? Then just pry the old bearing out and fit the circlips? Could be difficult to get the old one out, it will be in by about half its depth.

Thoughts

bill · Nov 5, 2013

how about using a socket that the hub will just fit into.

Cowboy Don said:
Here's what I'm thinking, after fitting the bearing to the hub, I fit the old bearing in behind it to provide support while driving the centre in? Then just pry the old bearing out and fit the circlips? Could be difficult to get the old one out, it will be in by about half its depth.

Thoughts

Al-otment · Nov 5, 2013

Once you've installed the bearing into the chainwheel with circlip, you could then put the hub in the freezer for an hour or so. While the hub is freezing you then gently heat the chainwheel c/w bearing. With a bit of luck the hub should require minimal force to fit.

Using a press is a gentle way of assembling bearings etc.

By the way, the hub surface where the inner race sits looks a bit shiney, possibly due to bearing inner race spinning on the hub. Could create play at chainwheel when assembled. Might be worth replacing.

Torontonian · Nov 5, 2013

I see clutch center notching going on. Can you post a better picture so we can gauge the depth of those notches ? Of course some know the answer in advance re: replacement.

comnoz · Nov 5, 2013

My suggestion would be to heat the clutch drum to 350 degrees F. and drop the bearing in. It will slip into place if everything is clean and lightly lubed.

Then support the bearing by it's inner race with a piece of tubing and press the center in.

No need to cool the center. Even if you cool it to 0 degrees the change in size would only be .0003 Inch, which is hardly worth it.

If you support the bearing by its outer race when you press the center in the balls will make dents in the races and lead to early failure. Jim

pete.v · Nov 5, 2013

Torontonian said:
I see clutch center notching going on. Can you post a better picture so we can gauge the depth of those notches ? Of course some know the answer in advance re: replacement.

I agree, that clutch center is trash. This is a Classic example of a bad one.

Al-otment · Nov 5, 2013

comnoz said:
My suggestion would be to heat the clutch drum to 350 degrees F. and drop the bearing in. It will slip into place if everything is clean and lightly lubed.

Then support the bearing by it's inner race with a piece of tubing and press the center in.

No need to cool the center. Even if you cool it to 0 degrees the change in size would only be .0003 Inch, which is hardly worth it.

If you support the bearing by its outer race when you press the center in the balls will make dents in the races and lead to early failure. Jim

Despite my previous post I have to say I agree with Jim's comments above.

Torontonian · Nov 5, 2013

New circlip behind basket tightened less than stoopid book suggests. New hardened center (soo soory to bring it up , $ to you ) and $INCE you're in there more forgiving plate$ on that center. :?

Cowboy Don · Nov 6, 2013

Thanks guys, so best to devise something that just supports the inner race as I fit the clutch centre to it?

Don't worry about the notches, new centre is on the cards and am just trying to get things figured out first.
Only concern is, will a stock centre work with my belt drive kit?

comnoz · Nov 6, 2013

Cowboy Don said:
Thanks guys, so best to devise something that just supports the inner race as I fit the clutch centre to it?

Don't worry about the notches, new centre is on the cards and am just trying to get things figured out first.
Only concern is, will a stock centre work with my belt drive kit?

Only concern is, will a stock centre work with my belt drive kit? Yes

rvich · Nov 6, 2013

My clutch center looked much the same when I tore my bike down. Which is a little surprising given the low milage and the fact that when I put a file on it I couldn't make any progress in cleaning up any of the notching. Whether or not attempting to clean it up is a good or bad idea can be debated elsewhere. I just never throw anything away without looking at the options. This spoke volumes to me about those heavy clutch plates.

So has anybody ever devised a decent way to try and repair the notching? I assume not. But it never hurts to ask. Those things are kinda dear!

Russ

texasSlick · Nov 6, 2013

rvich said:
My clutch center looked much the same when I tore my bike down. Which is a little surprising given the low milage and the fact that when I put a file on it I couldn't make any progress in cleaning up any of the notching.

So has anybody ever devised a decent way to try and repair the notching? I assume not. But it never hurts to ask. Those things are kinda dear!

Russ

Hard chrome plating can fill the notches. Next, it has to be ground down to size.....this can be the expensive part of the refurbishment. It becomes a choice of buying a new center for less money, suffering future notching, or going with the hard chrome that should give longer service. Take the center to a machine shop to get an estimate on grinding before committing to plating. If you can find a shop equipped to do the work at a reasonable price, get them to take the dimensions off the center before plating.

Slick

Bob Z. · Nov 6, 2013

If I remember correctly, wasn't there an issue with 'hard' and 'soft' clutch centers back in the day?

Properly hardened metal would ring when tapped with a hammer.

Here's an old one of mine (I don't throw much away) that I had used a Dremel with rotary stone to round off the notches so
the clutch plates could disengage a bit easier. You can see the bronze color metal from the stock plates in the grooves.
The quick fix got me by a bit longer before I could get a new center.
This was back in the day when spare parts were more difficult to get than they are today.

Al-otment · Nov 6, 2013

texasSlick said:
rvich said:

My clutch center looked much the same when I tore my bike down. Which is a little surprising given the low milage and the fact that when I put a file on it I couldn't make any progress in cleaning up any of the notching.

So has anybody ever devised a decent way to try and repair the notching? I assume not. But it never hurts to ask. Those things are kinda dear!

Russ

Click to expand...

Hard chrome plating can fill the notches. Next, it has to be ground down to size.....this can be the expensive part of the refurbishment. It becomes a choice of buying a new center for less money, suffering future notching, or going with the hard chrome that should give longer service. Take the center to a machine shop to get an estimate on grinding before committing to plating. If you can find a shop equipped to do the work at a reasonable price, get them to take the dimensions off the center before plating.

Slick

Could be a good idea to get the plating done on a brand new hub. Should reduce free play between the plates and clutch hub. Reducing hammering effect from the plate 'tabs' on the clutch hub grooves.

Al-otment · Nov 6, 2013

Cowboy Don said:
Thanks guys, so best to devise something that just supports the inner race as I fit the clutch centre to it?

Don't worry about the notches, new centre is on the cards and am just trying to get things figured out first.
Only concern is, will a stock centre work with my belt drive kit?

Essential when fitting a belt drive to check that the gearbox mainshaft and crank drive shaft are parallel in two planes to each other. Otherwise causes problems with belt trying to run off the front pulley and ends up wearing rapidly, snapping or, I've read of a case where the belt 'jumped off' and wrapped it self around the stator, bending the crank drive shaft. Many owners say it's not worth checking, but ask them how many miles they do.

Hobot · Nov 7, 2013

Listee's gave bearing handling but as to measuring crank and basket squareness - forgetaboutit- on a belt as only way to get them right is to adj gearbox while turning and turning primary through enough times to see belt stays on basket, then start up to put in a spin and some heating to it to know its functionally square and ready for the road. Lines and lasers and carpenter squares are more than good enough for triplex forgiveness but dare ya to try an accurate measure only method then just ride off w/o doing a by guess and by golly, or guess what.. A belt can wad up most it mass pretty tight in the space between things at front. If ya can grab clutch and humanly detect a bit of slack you may be in for bad belt juju a ways from home or just can't keep belt on when testing before a ride.

Belt Drive Clutch Bearing Install

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